Answer: Cocoa Pods
In 1915, Coca-Cola held a competition to select a new eye catching bottle. They wanted a bottle so unique that, per the specifications of the contest announcement, people would recognize it by touch even in the dark. A team of designers from the Root Glass Company won the contest and the iconic and curvaceous Coke bottle as we know it entered into popular culture. The great irony of their design, however, is that they created it more or less by stumbling upon words in the general vicinity of “Coca” in a dictionary while at their local library.
While conducting research for their design, they found illustrations of cocoa pods from the cocoa tree. Although they knew that the cocoa tree had nothing to do with Coca-Cola (while it’s true that early Coca-Cola had small amounts of cocaine in it, cocaine is derived from the coca plant shrub, not the cocoa tree), they were taken by the symmetry, curves, and distinct ribs on the pod and used it as inspiration for the bottle.
Prior to the change, Coca-Cola used straight-walled bottles not unlike modern beer bottles and it would be very difficult to recognize those original bottles today save for well preserved labeling. From 1915 onward, though, the bottle became the most recognized in the world.
Image courtesy of Coca-Cola.